1. Field of the Invention
Embodiments of the present invention is related to an apparatus for a distributed antenna system (DAS), and more specifically, to a multi-carrier integration unit or band combiner unit (BCU) for a DAS, to facilitate more efficient multi-carrier service.
2. Description of Related Art
Distributed antenna systems (DAS) are utilized to provide more stable wireless mobile telecommunications services inside buildings, such as large stadiums, hospitals, hotels, campuses, etc. With an increasing number of mobile communication subscribers, the number of bands and carriers (e.g., wireless service providers) are also increasing. In view of this, support of multiple bands, as well as of multiple carriers, by a DAS may be becoming more desirable. Meanwhile, limiting use of a DAS to a single carrier may be less desirable in, for example, the aspects of resource efficiency and cost efficiency.
In general, a DAS is an apparatus for amplifying and transmitting signals so that base transceiver station (BTS) signals can reach RF shadow areas in large buildings and structures, and can also simultaneously be utilized for amplifying the signals transmitted by mobile stations (MS) or user equipment existing or located in the RE shadow areas, and for transmitting these signals to BTS in the opposite direction from the relay direction described above.
In a conventional DAS, RF units (RFU) located in head end (HE) units are assigned corresponding to each carrier and are respectively connected with a BTS or a bi-directional amplifier (BDA) corresponding to the carrier. The RFUs adjust signals received from the BTS or BDA to an appropriate level to transmit them to remote units (RU) via optic lines after electrical-to-optical (E/O) conversion and optic distribution.
A conventional DAS requires a plurality of RFUs in order to support multi-carrier service, because each RFU typically can only support one carrier. Accordingly, as the number of carriers increases, the number of RFUs used will generally increase. This may cause problems of increasing initial investment costs of the system, as well as operation costs, such as electrical bills, maintenance costs, and the like.